1. Technical Field
The present disclosure relates to a duplexed field controller. More particularly, the present disclosure relates to a duplexed field controller having two control units between which the control authority is switchable.
2. Related Art
According to a field controller in the related art, the same processing is simultaneously executed using two CPUs between which the control authority is switchable. When an abnormality occurs at a control side CPU, the control authority is shifted to a standby side CPU. With such duplexing CPU, the reliability of control can be significantly improved (see e.g., JP-A-2006-276958).
Also, in the duplexed field controller, since the continuity of control is required even at the switching of the control authority, it is desired to minimize the time during which control is intermitted. Moreover, the increasing control scan speed can be handled by smoothing the switching of the control authority.